1. Field of the Invention
The present invention relates to a catheter device for diagnostic, therapeutic and operative use in a duct or vessel of the body of a patient, particularly in ureter and urethra.
The device can be used for radiologic diagnosis in a duct. It can also be used for therapeutic purposes to bring pharmacological substances into a desired sector of a duct. It can also be used advantageously and in particular for removing stones from the urinary passages.
2. Description of the Prior Art
Catheter devices are well known from the prior art for operating in the ureter in order to carry out a mechanical extraction of calculi.
Among said devices, basket and loop catheters, catheters similar to the latter, but provided moreover with a dilator balloon, and catheters with two inflatable balloons are known, as well as a device formed by two catheters sliding one with respect to the other, each having an inflatable balloon at its end.
This catheter is described in U.S. Pat. No. 4,295,464. This device comprises two coaxial catheters, of which the inner and thinner one is introduced, with the balloon deflated, until above the ureter sector in which the calculus is sited. The second catheter, which slides over the first one, is positioned in such a way that its end is below the position of the calculus. Then the balloon which is on the tip below the calculus is inflated. The balloon is inflated gradually until a muscle relaxation of the ureter sector involved is obtained. Successively the balloon of the first catheter is inflated and it is manipulated, also with the aid of strings connected thereto, thus trying to detach the calculus from the wall of ureter sector and cause it to fall downwards. Having obtained this result, the balloon of the second catheter is deflated and brought to a lower position, where it is inflated again. Then the upper catheter is also lowered to try and push the calculus downwards. The above operations are repeated in succession, until the expulsion of the calculus from the orifice of the ureter is obtained. The aforementioned device operates on the calculus by means of a mechanical force which has the function of detaching the calculus from the wall of the ureter and dragging it down. The enlargement of the ureteral passage obtained by the dialating balloon serves the purpose of preparing an easy passage for the calculus, however it has to be observed that it does not act on the ureteral sector in which the calculus is housed, when said calculus remains fixed in its seat. In that case, in fact, the calculus is held blocked to the ureteral wall by an edema which the calculus itself has produced. Consequently a purely mechanical extraction by means of a downwardly directed force on the calculus can produce abrasions and dilaceration of the ureteral wall and very often simply does not succeed.